package day21_28.day22;

import java.util.*;

public class Main02 {
    public static void main(String[] args) {
        Scanner scn = new Scanner(System.in);
        StringBuffer stringBuffer = new StringBuffer();
        int num = 0;
        Map<Character , Integer> map = new HashMap<>();
        String str = scn.next();
        StringBuffer strB = new StringBuffer();
        for (int i = 0; i < str.length(); i++) {
            map.put(str.charAt(i) , map.getOrDefault(str.charAt(i) , 0) + 1);
        }
        for (Map.Entry<Character , Integer> set : map.entrySet()
             ) {
            if (set.getValue() == 1){
                stringBuffer.append(set.getKey());
                num ++ ;
            }
        }
        if (num == 0){
            System.out.println(-1);
        }
        for (int i = 0; i < stringBuffer.length(); i++) {
            System.out.println(stringBuffer.charAt(i) + " ");
        }
    }
}
